The Distribution of Posthodiplostomum Cuticola and Rossicotrema Donicum in Scardinius Erythrophthalmus and Hypophtalmichthys Molitrix Stemming from the Danube Delta

Abstract

We investigated the pathogenicity of Posthodiplostomum cuticola and Rossicotrema donicum digenean infestations within freshwater fish populations, in the Gorgova – Uzlina, Dunavat – Dranov and Razim – Sinoie natural complexes. The so-called “Black spot disease” caused by the metacercarial infestation was diagnosed in 5 out of 11 studied freshwater fish species: rudd (Scardinius erythrophthalmus), silver carp (Hypophtalmichthys molitrix), zarte (Vimba vimba), bream (Abramis brama) and European perch (Perca fluviatilis). The metacercariae were found mostly on the surface of the body (on fins, scales and skin), but also in the mouth, gills, eye sockets and even within the muscle, underneath the skin. Additionally, prevalence of the disease was estimated in rudd and silver carp during a 6-year study period. It resulted a maximum prevalence of 33.44% in the silver carp caught in Dunavat – Dranov (during the 5^th year of the study) and a minimum prevalence of 22.81% in the rudd caught in Gorgova – Uzlina  (during the 6^th  year of the study).